Preparing tar for use on roads



" *The waxy fraction Patented July 31, 1934 PATENT orrrc PREPARING TAR roa USE ON noAns Carl Oscar Condrup, London, England, assigncr to Thermal Industrial & Chemical (T. I. 0.)

Research Company Limited, Allington House,

London, England No Drawing. Application June 16, 1930, Serial No. 461,635. In Great Britain August 6, 1929 16 Claims.

Certain tars are ill-suited for preparation as road tar or for application to roofing and similar surfaces, either owing to their containing waxy matter, or because they are not of a sticky character, evenwhen wax-free, and it is the object of this invention to treat such tar so as to obtain a satisfactory road tar of a strongly adhesive nature. r I

It is known that tar may be separated into oils and acid tar by treatment with acid, such as sulphuric acid, and no claim is herein made to such treatment per se.

For the purpose of this invention the tar is first subjected to an acid treatment whereby there, isproduced. a layer of oils and a layer of acid .tar which are duly separated. Sulphuric acid, either in a concentrated or weaker state, is preferably used in the treatment; for the sake of economy an acid of gravity 140 'Iw. (1.70 sp. gr.) may advantageously be employed. The acid isbest applied at l20-180 F., and may amount to less than 1 per cent. of the weight, of the crude tar, although on occasion it may be more.

The acid treatment is followed by 11611131331123,

' tion of the acid tar, and the process may be car ried out by the following alternative treatments: i

. (a) In the-case of non-waxy tars of a character not requiring the elimination of any heavy oils, the. layers oioils and acid tar are not separated, but the mixture is neutralized, dehydrated and partially distilled sons to remove light oils and thereby attain the desired consistency.

(b) In the case of non-waxy tars of a character requiring the elimination of some heavy oils, the layers, of oils and acid tar are separated. The oils, preferably after neutralization, are fractionated in order to segregate those oils which distill between, say, 325 and 395 C. The acid tar, after neutralization, dehydration and partial distillation, is mixed with the fractionated oils and distillation residue (except those oils distilling between, say, 325 and 395 (1.). Finally, if necessary the mixture is subjected to partial distillation and heat treatment to obtain the desired consistency.

(c) For waxy tars, the layers of oils and acid tar are separated.

The oils are distilled (preferably after neutralization with ammonia or other alkali) to obtain oils free from wax (generally a fraction boiling below 325 (3.), waxy oil (generally a fraction boiling between 325 and 395 C.) and a resinous residue.

can generally be further separated by centrifuging into a waxy concentrate and oil comparatively free from wax, which oil may sometimes be added to the first fraction.

When substantially complete removal of wax is not the aim, the acid tar is neutralized and de' hydrated and is distilled to an extent sufiicient to remove excess of tar acids. Wax-free oils are then mixed. in, in amount depending upon the consistency required, and heat treatment may, or i i may not be given for controlling the consistency; such treatment, if given, (and this applied also to case (b) above) may consist in heating the mixture for some time to a temperature of, or below, its boiling point. The sequence of operations may be varied.

When substantially complete removal of the wax is an object, it is preferable to extract the acid tar by wax-free oils, and allow to settle. If separation into acid tar and oils does not occur by mere settlement, then further acid may be added to effect the separation of the acid tar and oils.' These oils are mixed with the original oils from the first acid treatment, if available, or with corresponding oils. The final acid tar is worked up to road tar as described above.

Another alternative is to add wax-free oils to the crude tar, and carry out the acid treatment.

Frequently the oils free from'wax exceed the proportion required for mixing with the Worked up acid tar and the resinous residue, in which case the excess may be used for other purposes. For example, the distillation or iractionating process may stop short at a stage at which the wax-iree'oils have come over in amount sufficient for subsequent incorporation with the treated acid tar, and the residue containing waxy oil and resins may be used, erg. for grease manu-. facture, fuel oil or crackingv stock. a v

In an alternative method of using the acid the l whole of the acid subsequently required for treating the crude tar is used for refining the .oils separated out from the crude tar by the acid treatment and the acid sludge resulting from the refining is used for treating the crude tar to separate it into layers. Obviously this meth- 190 0d. of using the acid cannot be applied in starting up a plant, as no oily layer is available to refine, and the first charge of crude tar would therefore be treated by the direct addition of raw acid. x

The consistency of the final road tar depends mainiy on the strength and proportion of the acid used in the acid treatment and on the temperature of this treatment, and any subsequent heat treatment.

Either with waxy or wax-free crude tars the invention involves the working up, for the purpose of rendering them useful for application to roads or to roofing or to similar purposes, tars which have been treated with acid or acid sludge.

The process described is applicable to the treatment of all tars which either contain waxy matters or one not of a sticky character, such as water gas tar, blast furnace tar, peat tar, lignite tar, low temperature carbonization tar, and some high temperature carbonization tars.

While the invention has been described with special reference to the preparation of road tars, it is to be understood that it is equally applicable to the preparation of tar for other purposes, e. g. pitch or roofing tar.

Having thus described the nature of the said invention and the best means I know of carrying the same into practical effect, I claim:

1. The method of obtaining a satisfactory road tar of a strongly adhesive nature, which consists in adding a quantity of sulphuric acid of the order of 1 per cent by weight, to a crude tar, agitating the resulting mixture at a temperature of 120-180 F., neutralizing the mixture of oils and acid tar (whether previously separated and re-admixed or not), by adding an alkali thereto and dehydrating it, and finally, heating it to volatilize the light oils and obtain the desired consistency.

2. The method of obtaining a satisfactory road tar from crude tar free from waxy matter, which consists in agitating the tar, in known manner, with a small proportion of acid, preferably sulphuric acid at a temperature between 129-180 F., permitting the tar so treated to settle into a layer of oils and a layer of acid tar, fractionating the oils (preferably after neutralizing) in order to segregate those oils which distill between temperatures of 325 and 395 C. under atmospheric pressure, mixing the acid tar after neutralization, dehydration and partial distillation with the distillation residue and the fractionated oils (except those oils distilling between, say, 325 and 395 C.) and finally, heating the mixture to reduce it to the desired consistency.

3. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, which consists in treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid at a temperature of 120 F.-l F., permitting the treated tar to settle into a layer of oils and a layer of acid tar, fractionating the oils preferably after neutralizing and thus obtaining oils free from wax, waxy oils and a resinous residue, mixing the acid tar after neutralization, dehydration and partial distillation, with a proportion of the wax-free oils and the resinous residue and finally heating the mixture to obtain the desired consistency.

4. A modification of the method of claim 3, wherein the acid sludge resulting from the refining of the oils is used in place of raw acid.

5. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid at a temperature of 120 F.-180 F.; permitting the tar so treated to settle into a layer of oils and a layer of acid tar; fractionating the oils so obtained, preferably after neutral izing, into oils free from wax, waxy oils and resinous residue; admixing the acid tar with a proportion of the wax free oils; allowing said mixture to settle into a layer of acid tar and oils;

neutralizing, dehydrating and partially distilling the tar; mixing such tar with the wax free oils and resinous residue, and heating such mixture to reduce it to the desired consistency.

6. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid; permitting the mixture to settle into a layer of oils and a layer of acid tar; neutralizing the oils so obtained and fractionating them to obtain oils free from wax, waxy oils and resinous residue; centrifuging the waxy oils into a waxy concentrate and oil comparatively free from wax; neutralizing, dehydrating and partially distilling the acid tar; mixing such acid tar with the oils free from wax and resinous residue obtained by said fractionating step and the last-named oil; and heating such mixture to reduce it to the desired consistency.

7. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid; permitting the treated tar to settle into a layer of oils and a layer of acid tar; fractionating the oils so obtained, preferably after neutralizing, to obtain oils free from wax, waxy oils and a resinous residue; mixing a proportion of the oils freed from wax with the acid tar; subjecting such mixture to a further acid treatment to separate it into a layer of acid tar and oils; neutralizing, dehydrating and partially distilling such acid tar; admixing the acid tar, the wax-free oils obtained by the second acid treatment, the wax free oils and resinous residue obtained by the first acid treatment; and heating such mixture to reduce it to the desired consistency.

8. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising adding wax-free oils to the crude tar, treating such mixture in known manner with a small proportion of acid, preferably sulphuric acid, permitting said mixture to settle into a layer of oils and a layer of acid tar, fractionating such oils, preferably after neutralizing, to obtain oils free from wax, waxy oils and a resinous residue; neutralizing, dehydrating and partially distilling the acid tar; mixing the tar with the wax-free oils and resinous residue; and heating such mixture to reduce it to the desired consistency.

9. The method of obtaining a satisfactory road tar of a strongly adhesive nature which consists in adding a small proportion of acid, preferably sulphuric acid, to a crude tar to separate such tar into oils and acid tar, neutralizing said oils and separating them into oils free from wax, waxy oils and a resinous residue, mixing the oils free from wax with the acid tar, dehydrating such mixture and heating same to reduce it to the desired consistency.

10. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, which consists in treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid, permitting the treated tar to settle into a layer of oils and a layer of acid tar, fractionating the oils preferably after neutralizing and thus obtaining oils free from wax, waxy oils and a resinous residue, and mixing the acid tar after neutralization, dehydration and partial distillation, with the wax-free oils and the resinous residue.

11, The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid; permitting the tar so treated to settle into a layer of oils and a layer of acid tar; fractionating the oils so obtained, preferably after neutralizing, into oils free from wax, waxy oils and resinous residue; admixing the acid tar with the wax free oils; allowing said mixture to settle into a layer of acid tar and oils; neutralizing, dehydrating and partially distilling the tar; and mixing such tar with the wax free oils and resinous residue.

12. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid; permitting the mixture to settle into a layer of oils and a layer of acid tar; neutralizing the oils so obtained and fractionating them to obtain oils free from wax, waxy oils and resinous residue; centrifuging the waxy oils into a waxy concentrate and oil comparatively free from wax; neutralizing, dehydrating and partially distilling the acid tar; and mixing such acid tar with the oils free from wax and resinous residue obtained by said fractionating step and the last-named oil.

13. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising treating the crude tar in known manner with a small proportion of acid, preferably sulphuric acid; permitting the treated tar to settle into a layer of oils and a layer of acid tar; fractionating the oils so obtained, preferably after neutralizing, to obtain oils free from wax, waxy oils and a resinous residue; mixing a proportion of the oils freed from wax with the acid tar; subjecting such mixture to a further acid treatment to separate it into a layer of acid tar and oils; neutralizing, dehydrating and partially distilling such acid tar; and admixing the acid tar, the wax-free oils obtained by the second acid treatment, and the wax-free oils and resinous residue obtained by the first acid treatment.

14. The method of obtaining a satisfactory road tar from crude tar containing waxy matter, comprising adding wax-free oils to the crude tar, treating such mixture in known manner with a small proportion of acid, preferably sulphuric acid, permitting said mixture to settle into a layer of oils and a layer of acid tar, fractionating such oils, preferably after neutralizing to obtain oils free from wax, waxy oils and a resinous residue; neutralizing, dehydrating and partially distilling the acid tar; and mixing the tar with the wax-free oils and resinous residue.

15. The method of obtaining a satisfactory road tar of a strongly adhesive nature which consists in adding a small proportion of acid, preferably sulphuric acid, to a crude tar to separate such tar into oils and acid tar, neutralizing said oils and separating them into oils free from wax, waxy oils and a resinous residue, mixing the oils free from wax with the acid tar, and dehydrating the mixture.

16. The method of obtaining a satisfactory road tar from crude tar free from waxy matter, which consists in agitating the'tar, in known manner, with a small proportion of acid, preferably sulphuric acid at a temperature between 120180 F., permitting the tar so treated to settle into a layer of oils and a layer of acid tar, fractionating the oils, preferably after neutralizing, in order to segregate those oils Which distill between temperatures of 325 and 395 C. under atmospheric pressure, and mixing the acid tar after neutralization, dehydration and partial distillation with the distillation residue and the fractionated oils (except those oils distilling between, say, 325 and 395 0.).

CARL OSCAR CONDRUP. 

